Method of coating thermoplastic material and article produced thereby



Mamh 4, 1953 L F DOSMANN 2,825,661

METHOD OF' COATIG THERMOPLASTIC MATERIAL AND ARTICLE PRODUCED THEREBY Filed Sept. lO, 1954.

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ATTORNEY United States Patent F METHD OF COA'NG THERlt/UPLASTIC MATE- RIAL AND ARTICLE PRGDUCED THEREBY Lucian P. Dosinann, South Bend, Ind., assigner to United States Rubber Company, New `ltorlr, N. Y., a corporatron of N ew Jersey Application September l0, 1954, erial No. 455,182 9 Claims. (Cl. 117-1383) This invention relates to a method of providing a pro` tective and decorative coating on a normally hard, tough, thermoplastic base material, the principal components of which are a styrene-acrylonitrile resinous copolymer and 'outadiene-acrylonitrile rubbery copolymer in uniform homogeneous admirture with one another or a styreneoutadiene resinous copolymer and a butadiene-styrene robbery copolymer in like admixture with one another, and to the resulting article of manufacture.

A material which has attained considerable importance is a normally hard, tough, thermoplastic ma- Lerici composed essentially of a uniform thermoplastic mixture of from 60 to 90% of a resinous copolymer or styrene and acrylonitrile in proportions of from 50 to 90% of styrene, and from 50 to 10% of acrylonitrile, and from 40 to 10% of a rubbery copolymer of butadiene and acrylonitrile, i. e., the material commonly referred to as N, which usually will be a copolymer of from l to 40% of acrylc-ni. ile and from 85 to 60% 'of butadiene and often will contain from 40 to 100% of methyl ethyl ketonednsoluble gel, which may be imparted in the way described in Romeyn et al. U. S. Patent No. 2,597,951. Small amounts of pigments (which term t' use to include fillers) may be included in the mixture. For further details regarding normally hard, tough, thermoplastic mixtures of styrene-acrylonitrile resinous copolymers and butadiene-acrylonitrile rubbery copolymers attention is directed to U. S. Patents Nos. 2,439,202, 2,505,349 and 2,550,139 to L. E. Daly and No. 2,600,024 to Romeyn et al. The proportions of the resinous and rubbery copolymers are by weight based on the sum of the two copolymers.

Another plastic material which has also attained importa-nce is a normally hard, tough, thermoplastic material composed essentially of a similar mixture of from 60 to 90% of a resinous copolymer of styrene and butadiene, which typically is a copolymer of from 75 to 95% of styrene and from 25 to 5% of butadiene, and from 40 to 10% of a robbery copolymer of butadiene and styrene, which typically is ya copolymer of a major proportion of butadiene and a minor proportion of styrene, this component being commonly known as GR-S. These blends may or may not be vulcanized in the iinal sheet or shaped article. it is often preferable that they be unvulcanized so that scrap sheet or molded articles can be re-worked into new sheets or molded articles.

The plastic materials mentioned above are often sold in the form of sheets, typically having a thickness of from V16 to 1/4 of an inch, these sheets often being made by plying up under heat and pressure a plurality of layers of thin calendered sheets of the base stock. Articles of varying shapes are made from these sheets by drawing in the known manner. in some cases the aforementioned mixtures or" resinous and robbery copolymers are supplied in the form of granular molding powders which are often molded by conventional techniques to form articles having the desired shape.

The problem has arisen of providing a decorative and 2,825,661 Patented Mar. 4, 1958 ICC protective coating for sheets or shaped articles made of normally hard, tough blends `of the aforementioned resinous 'and rubbery copolymers. Heretofore, in order to provide the cus-temer with a sheet or molded article having the desired color it was necessary to compound an undesirably large number of differently colored stocks of the resin-rubber mixture. lt has been recognized that, if it were commercially feasible to do so, it would be desirable to make sheets or articles of stocks of only a relatively small number of basic colors, say abou-t l0, and to provide a lacquer which could be applied to the finished sheet or drawn article or molded body to give the additional colors desired. The properties required of such a lacquer are that it adhere tenaciously vto the resin-rubber blend and that it stand up well upon prolonged `exposure to the weather. Heretofore no lacquer having these properties was known to those confronted with the problem.

Another problem encountered with articles of the aforementioned resin-rubber blends is that when they are used outdoors the action of the elements causes a phase separation on the surface. Apparently outdoor exposure changes the rubber or resin or both in such a Way that they become incompatible and actually form separate phases. This phase separation is highly objectionable because of the unattractiveness .of the surface of the article which has undergone it.

Attempts have been made to overcome the aforementioned difliculties by coa-ting the surface of the sheet or article with a pigmented coating composition. However, the generally available lacquers and coatingV compositions have been wholly unsatisfactory for this purpose. The `ordinary lacquers do not prevent or cover up the phase separation 'and they deteriorate or darken objectionably upon outdoor exposure. In addition, normal lacquers chip oilc the coated body under ordinary conditions of handling and use and this of course is highly objectionable.

The principal object of the present invention' is to provide 4an improved coating Afor sheets or articles formed of normally hard, tough, thermoplastic mixtures-of a styrene-acrylonitrile resinous copolymer and a butadieneacryloni-trile rubbery copolymer or of a styrene-butadiene resinous copolymer and a butadiene-styrene rubbery copolymer. Another object is to provide a coating which can be easily applied by ordinary coating techniques, which prevents the above-mentioned phase separation, which provides a highly attractive surface finish, which enables the manufacture of the underlying sheet or body in only a relatively small number of basic colors and yet enables the manufacturer to readily provide an article having any desired color, which provides a coating which is permanently attractive e en under conditions of routdoor exposure, and which tenaciously adheres to the underlying resin-rubber body. Another object is to pro- Vide a coating which promotes superior outdoor aging of these rubber-resin blends, and which protects the surface of such blends against bloom, surface erosion, Water spotting and discoloration over prolonged outdoor aging, for a period of say one year, in Florida. Numerous other objects of the present invention will more fully hereinafter appear.

In the accompanying drawing there is portrayed diagrammatically a section of thermoplastic base sheet 1 of a rubber-resin blend having an overlying surface coating 2 in accordance with the present invention. Reference numeral 3 represents the interface between the thermoplastic base sheet and the overlying surface coating.

The present invention is based upon my discovery that the foregoing objects can be accomplished in a simple and commercially feasible manner by providing on the surface of 4the thermoplastic base sheet or molded body Vamalgam of a normally hard, tough uniform mixture of the kind indicated above, a continuous layer of a Composition comprising a resinousY copolymer of Vvinyl chloride an triluorochloroethylene.V p f In practicing Vmy invention I` apply tothe surface of the body of resin-'rubber blend a lacquer comprising a clear or apigmented solution of the resinous'copolymer. of VvinylY chloride and triuorochloroethylene in a volatile organic solventtherefor, and to evaporate the solvent to deposit a continuous layer ofvinyl chloride-trifluorochlorethylene resinous copolymer on the surface. Only a. single application of the lacquer, resulting in a very thin'V layer of the resinous copolymer, will suiice lfor Vsome purposes, but for best results, especially when the coated article isto be used in contact with hot Water, I Yapply several coats. Y y

Ifnd that especially good results Vare -obtained if the lacquer used Yin the first coat at least, and preferably in all coats in the interest of simplicity, is made by dissolvingV the vinyl chloride-trfluorochloroethylene .resinous` copolymer in a solvent composed of a major proportion of an organic liquid which is substantially a non-solvent for (i. e..exerts substantially no solvent or swelling action upon) kthe rubbery Vand resin components of the base materialand aminor proportion of an organic liquid whichis a good solvent `for at least one, and preferably both,' of the resin and rubber components of the base material. The proportion of the latter ingredient inthe solvent should be sufficiently great to cause the mixed.

lacquerV solvent to attack the base but not so great as to top color sheet when plying up several layers of rubberresin sheet under heat and pressure to form thicker` sections. Application of the lacquer at the calendar enables a substantial reduction in cost as compared to pigmenting the entire rubber-resin mixture and enables theY number of differently colored rubber-resin mixtures to be reduced to a few basic colors.

be equal to from 5 to 15% by weight. When a pigobjectionably impair the properties ofthe surface of the base. I have found that use of such a mixed solvent gives remarkably good adhesion of the pigmented vinyl chloride-tritluorochloroethylene resinous copolymer lm to theunderlying base. For example, I have obtained unusually satisfactory results by/'using 'as the solvent mented lacquer is used, the concentration of pigment in the lacquer should be sufliciently great to completely mask the surface of the underlying body. It will often be found preferable to use a weight concentration of pigment somewhat less than the resin concentration. Typically the pigment concentration will range from 5 to 13% by weight of the lacquer. l prefer to measure the relative proportions of pigment and resin by volume, as isV explained in detail below.

The solids content of the lacquer will depend upon the method of coating used but will usually range from l0 to 25% by weight.

As has been indicated, the'lacquer can be clear orV pigmented. Those skilled in the Yart can readily determine whether a clear or a pigmented coatingV should be applied and the quantity, quality andy type of pigment l which should Vbe used in pigmented lacquers in the light of the following considerations. Although theY vinyl chloride-triuorochloroethylene Vresinous copolymer is itself stable to any colorlchange on Vexposure to ultramedium for -,the lacquera mixture of from S5 to 967%V by weight of a material which is substantially a nonn solvent for the resin or rubber componentsof the base and a'good solyentfor the vinyl chloride-trifluorochloroethylene copolymer, an example of'such a material being toluol, and from l5 to 4%Y ofmaterial which is'a powerful solvent for at leastone of the Vresin and rubber components of the base and a good solvent for the vinyl chloride-tiiuorochloroethylene` copolymer, any example of the( latter material-being afsaturatedaliphatic Vketone such4` asmethyl ethyl ketone or methyl Visobutyl ketone'. Theindicated proportion'ofk the lsolvent for'the base materials is greatenoughkto cause the coating composi- V \tion to attack the base and give good adhesion but not so great as Vto cause softening'of the surface ,of the base.

VVIt should be pointed out that the use of an ,active solvent which willtattack the base as alcomponentv ofthe lacquer solvent is'not essential. I have obtained very good results using a lacquerwbich doesY not contain such an active solvent. l Y

V In the typical practiceV of my invention, I make up a lacquer v ,comprising the vinyl .chloride-triiluorochloroethylene vresinous. copolymer,V pigment `(if used), and

, mixed Ysolvent andapply this to the surface of the pre-Vw viously formedbody of the resin-rubber blend. Any

suitable coating method such VVas spraying, brushing, doctor1ng`.(kn1fejcoating),.squeegeeing or the'like can Vbe used, 1t being understood that the lacquer should be formulated with reference to the coating method to beV used. In the'casevof at sheets of resin-rubber mixture,

the lacquer could conceivably be applied by doctoring orV roller Acoating (as with a lambs wool roller coater) or srmllar Vmethods commonly used for applying lacquers to at materials. If desired, the lacquer composition can Ybe applied to the Yresin-rubber sheet as the latter comes from the calender by which it was formed. Application (aSby roller coating) of the lacquer at the calender which forms the rubber-resin sheet is often advantageous in that Y it enables theljcoated sheet thus obtained to bells@ s? violet light, a slight yellow tint, caused byY its refractive index, is apparent in a Vclear coating over white rubberresin'blends. Thereforefor the production of white or pastel shades it is highly preferred to pigment the lacquer coating with titanium dioxide or with titanium dioxide and the desired-colored pigments, respectively. The effectiveness-of clear coatings is influenced by the color pigments in the rubber-resin base,'varying with the quantity, quality and type of such pigments.V Clear coatings will not adequately protect rubber-resin'` blends of low (2.5 to 3.0 parts per parts of rubberV plus resin) pigment` concentration from discoloring but effectively protects rubber-resin blends of high pigment concentration which ordinarily discolor'from outdoor ultraviolet aging though not as rapidly as blends ofY low pigment concentration. When clear lacquers are used, the

pigment concentration Yin the rubber-resin-blend shouldV be high (3.5 or more parts per l0() parts of rubber-plusV resin).

should be heat-stable to withstand Ythe heat of mixing, Yshaping and embossing. l Y f TheV pigments ,usedrinthe rubber-resin blend The Vinyl chloride-triuorochloroethylene resinous copolymer is Vcompletely stable and non-reactive to color pigments. VI prefer to make the'pigmented lacquers by grinding the resinous copolymer, solvent and color pigment together in a paint or ball mill. Examples of suitable pigments' are cadmium pigments (other than cadmiments can be used in the rubber-resin blends in the Vcase where aclearprotective lacquer is used.y

Y The amount of pigment that can be added to the vinyl chloride-trifluorochloroethylene resinous copolymer can vary widely depending upon thek color intensity of the satisfactory. These pigment ratios are for any typefof um yellow), carbon blacks, titanium dioxide, iron ypig- Y ments in all Vshades and chrome green. The same pig-Y Generally speaking, volume ratios of pig-V ment toresinous copolymer of from 0.15zlV to 0.4:1 areVY Y '5 filler material and are not confined strictly to color pigments. With pigments of high color strength a ratio of 0.16:1 gives optimum gloss and color, and with increasing ratio loss of gloss and resistance to water spotting and cleaning results. With pigments of low color strength higher ratios give optimum results.

The vinyl chloride-triuorochloroethylene resinous copolymer is soluble in all of the common ketone, aromatic hydrocarbon and chlorinated solvents commonly used in making lacquers. The type of solvent blend used will determine the spraying characteristics. The following solvent blend has been found to produce fast-drying, nonsagging coatings with good ow-out properties and with good adhesion to the surface of the rubber-resin blend without inducing permanent softening which would be objectionable:

The addition of a small amount, say 0.1% by weight based on the vinyl chloride copolymer, of a silicone fluid (e. g., that sold as DC-200 silicone uid) in formulating the lacquer helps flow-out particularly if silicone oil be present on the surface of the rubber-resin blend.

lf the rubber-resin surface is contaminated with foreign material, such as oils, wax, lint, etc. as a result of preceding operations, it is essential that it be Washed with a suitable material such as isopropyl alcohol prior to spray application of my lacquer. en my lacquer is applied by brushing, squeegeeing, knife coating, roller coating, or the like, such preliminary washing is unnecessary.

A high percentage of ketones in the solvent mixture should be avoided particularly where the lacquer is applied by a method involving relative movement of surface and application such as brushing, squeegeeing, knife coating, etc., in order to avoid permanently softening the surface of the rubber-resin mixture. Smaller concentrations of ketones are desirable in that they increase the bite or adhesion of the lacquer to the smooth rubber-resin surface.

lf a dull lacquer is desired it may be produced by incorporation of zinc stearate in the lacquer. Twenty parts of zinc stearate by weight based on the weight of the vinyl chloride-triuorochloroethylene copolymer gives excellent results. The amount may vary from l to 25 parts. For good dispersion the zinc stearate is dissolved in the aromatic hydrocarbon portion of the solvent and the resulting solution is then um'formly incorporated with the other ingredients, namely the resin and balance of solvent and pigment (if used). if pigment is used the entire lacquer is preferably ground before use.

it is diicult to state exactly the thickness of the protective and decorative layer applied in accordance with my invention. The thickness will lvary with the mode of application. The thickness of the layer will usually be equal to at least 1.0 mil and it may range upwardly from this value to 50 mils. The thickness of the layer will be thin relative to the thickness of the underlying resin-rubber body. Generally speaking, the thickness will correspond to an appli-cation of from 1/2 to 2 ounces of vinyl chloride-triiuorochloroethylene copolymer per square yard of base surface. Levels equal to one ounce per square yard of dry pigmented lacquer or two-thirds of an ounce per square yard of dry, clear lacquer are recommended. It will be understood that in the case of sheet material one or both faces may be provided with my coating and that in the case of a drawn or molded article the entire surface thereof or only the portion which is most exposed to weathering may be coated with the lacquer.

The details of the manufacture of the resin-rubber body to be protected need not be set forth because they are fuly described in the prior art. It will usually consist essentially of the resin and rubber, and pigment (if it is pigmented). The amount of pigment will usually not exceed 10% by weight based on the sum of resin and rubber.

The vinyl chloride-triuorochloroethylene resinous copolymer is a material well known to those skilled in the art. it can be made in a manner generally similar to that shown in the abstract of abandoned United States application Serial No. 194,023, filed November 3, 1950, published in the Oicial Gazette for February 17, 1953, on pages 765766. Almost invariably it will contain from 5 to 95% of vinyl chloride and from 95 to 5% of triuorochlorocthylene and more commonly from y30 to of vinyl chloride and from 70 to 5% of triuorochloroethylene. These copolymers can be made by emulsion polymerization using a water-soluble free radical polymerization catalyst and preferably with incremental addition of vinyl chloride. An example of such a resin is that sold commercially as Exon 400 XR-61 made by Firestone Plastics Company, a division of Firestone Tire and Rubber Co. Exon 400 XR-l resin is supplied in a white powder form which can be easily dissolved in the solvent mixture to form the lacquer. Exon 400 XR- 61 was found by analysis to contain 60% vinyl chloride and 46% triuorochloroethylene. The vinyl chloridetriuorochloroethylene resinous copolymers are thermoplastic and are readily soluble in the usual aromatic hydrocarbon and ketone solvents. Their good solubility allows formulation in a solvent system which in addition to attacking the underlying resin-rubber body as mentioned above, meets the customary coating requirements and drying schedules. The applied lacquer coating does not require baking at a temperature sufficiently high t0 fuse the resinous copolymer. The lacquer dries rapidly to a tack-free surface in 20 minutes at room temperature. Full hardness is reached after overnight drying. Circulating hot air at 150 F. may be used to accelerate drying without blisters forming in the coating.

The physicial properties of Exon 400 XR-6l are as follows:

Specific gravity 1.74-.78. Relative viscosity (average) (1% solution in cyclohexanone) 1.5. Rockwell hardness R75 to R85. Cold crack temperature, C 24 to 20. Outdoor and indoor aging Excellent.

Dielectric constant (75 1:.-60 cycles) 2.84. D. C. resistivity (158 F.-60 cycles,

ohm/cm.) 5 1014.

The binding or film-forming component of the protective and decorative layer of my invention can consist of the resinous vinyl chloride-tritiuorochloroethylene copolymer. Alternatively, other binding or film-forming components compatible with the resinous copolymer may be used therewith in proportions ranging from a very minor proportion up to a proportion equal to that of the resinous copolymer. Examples of such other materials are alkyd or polyester resins, resinous acrylic acid ester polymers (e. g., polymethyl acrylate, polyethyl acrylate, ete), and silicone resins. The use of the resinous acrylic acid ester polymers is highly advantageous because it improves grease-resistance without reducing water-resistance or outside weathering properties.

in the typical practice of my invention, the underlying body will be manufactured in about 10 basic colors and around differently colored lacquer formulations will be provided, these roughly matching the ten basic colors and giving the necessary variety of colors required in the finished article. Thus the manufacture of the underlying jthe lacquer solvent by evaporation, there was .-7 bodyis greatly simplified and the number of rubber-resin stocks required tobe processed is greatly reduced with consequent large savings in the inventory and in scrap. Two-tone' effects can be achieved, `in the practice of my i invention, applying a pigmented lacquer over a suit- Vably embossed appropriately pigmented rubber-resin base and applying a clear protective over the entire surface. YThus a brown lacquer coat m-ay be squeegee-coated over a light tan basket Weave embossed rubber-resin surface and a protective clear lacquer coat sprayed over the entire surface.

for 12 months have` shown very little deterioration inV appearance whereas uncoated panels of the same blend showed very objectionable impairment in appearance when lexposedrunder the same conditions. The coating of my invention protects the surface of the rubber-resin blend against bloom, surface erosion, Water spotting and discoloration upon exposure to the elements overrlong Y periods of time.V

One of the most significant advantages of the use of vinyl chloride-triuorochloroethylene resinous copolymer is that coatings containing it adhere unusually wellKto lthe underlying resin-rubber body even after long exposure Vto the weather. To the best of my knowledge no other available coating material approaches the vinyl chloridetriiluorochloroethylene copolymer in this respect. I have tried many other materials but none of them has proved at all successful for this use.

An advantage of using vinyl chloride-trifluorochloroethylenerresinous copolymer as the sole film-forming or binding component of the protective layer is that the Vresulting layer is lireproof.

The vinyl chloride-triuorochloroethylene copolymer is thermoplastic and therefore the lacquered rubber-resin sheet can be deep drawn into shapes without anyV cracking or impairment of the coating. The lacquer coating is fully compatible with the rubber-resin blend and this makes it possible to re-work all process scrap.

Any of the conventional forming methods can be used i attractive appearance over 'a long period ofeweathering.

Blendsof styrene-acrylonitrile resinous copolymer andV `butadiene-zracrylonitrile robbery copolymer coated With a pigmented lacquer of my invention at a level of` one Vounce of solids per square yard have exhibited substantially Ano discoloration or water spotting after 500 hours/ina standard fweatherometerj indicating Ythe outstanding y V,value of my coating for outdoor applications. The Vlaf.:- quer prevents surface erosion and bloom which have I been serious problems in these blends. Surface erosion is actually a phase separation of the rubber and resinV which changes the refractive index of the surface. This phase separation is experienced when the rubber-resin blend is bent cold, or given a sharp impact, or exposed to outdoor weathering. The intimate adhesion of my lacquer coating to the rubber-resin blend appears to beV responsible for the prevention of the appearance of phase separation. Bloom apparently is produced from a migration of certain imcompatible ingredients in the resinrubber blend tothe surface and in some manner is prevented from appearing by my coating.l Y An accelerated test for determining the rate of develop- Vment of surface erosion on the surface of the blends of styrene-acrylonitrile resinous copolymers and butadieneacr'ylonitrile robbery copolymers involves the partial im- V:Ine'rsion of kstrips ofthe sheeted rubber-resin blend in v hesion is then determined after the 5 hour Water'test by applying Scotch pressure-sensitive adhesive tape across the lines of the samples. The tapeV is then removed with a quick jerk and any failurev of the lacquer bond is considered a failure of the coating. The sameV test can be used to determine dry (i. e. without water immersion) `adhesion of the lacquer to the Vrubber-resin blend. Un-

der-these tests, my coating exhibits remarkable adhesion' Except where otherwise noted, all proportions and percentages given herein are by weight.

Having thus described my invention, what I claim and Vdesire to protect by Letters Patent is:

n the drawing, reference numeral denotes the un- Aztec red (pigment) 150 Toluol-; 1600 Methyl ethyl ketone 100 VThis lacquer was sprayed onto the surface of a normallyrhard,.tough, thermoplasticbase sheet Vformed of a mixture of 70 parts of a resinous copolymer of Vstyrene and aci'ylonitrile containing 27-2870 acrylonitrile and 30 parts of a butadiene-acrylonitrile robbery copolymer containing about 62% of methyl ethyl ketone-insoluble gel and containing aboutV 30% combined acrylonitrile, together'with small amounts of pigment. Upon removing obtained anY articleVV which uponY prolonged weathering exhibit visible phase-separation. Some phase separation V'in the underlying bodygmay have occurred butit could not be seen through the coating. The lacquer coating did not. l

did'not chiplfrom the underlying body and retained its y 1.V A new article of manufacture comprising a norrnallyV hard, tough, thermoplastic body composed of a uniform thermoplastick mixture selected from the group consisting of mixtures of from V to 90% of a resinous copolymer of styrene andacrylonitrile, in proportions Yof Vfrom 50 to 90% of styrene and from 50 to 10% or" 55 mer of butadiene and acrylonitrile,rand mixtures of from '60 to 90% of a resinous copolymer of styrene and butaacrylonitrile, and from 40 to 10% of a rubbery copolydiene, in proportionsV of from to 95% of styrene and from 25 to .5% Vof butadiene, and from 40 .to V10% of la rubbery copolymer of butadiene and styrene, and Von the surface of said bodya relatively thin continuous layer of resinous copolymer consisting essentially of 5 to 95% Y Vvinyl chloride and from to 5%V triuorochloroethylene.

2. An article of manufacture as set forth in-claim 1 wherein said layer is pigmented. Y 3. VAn article of manufacture as set forth in Vclaim l Vwherein said layer is pigmented, the volume ratio of pig; ment to saidrlast-narn'ed resinous copolymer being equal posed of a uniform thermoplastic mixtureV selected from the group consisting of mixtures offrom 60to 90% of a resinous copolymer Vofstyrene and acrylontrile, in proportions of from 50 to 970% o f styrene and from 50'to of acrylonitrile, and from 40 to 10% of a rubbery copolymer of butadiene and acrylonitrile, and mixtures of from 60 to 90% of a resinous copolymer of styrene and butadiene, in proportions of from 75 to 95% of styrene and from to 5% of butadiene, and from 40 to 10% of a rubbery copolymer of butadiene and styrene, a relatively thin continuous layer comprising a resinous copolymer consisting essentially of from to 95% vinyl chloride and from 70 to 5% triuorochloroethylene dissolved in a volatile organic solvent for the last-named resinous copolymer, and evaporating said solvent to form a thin continuous layer of a resinous copolymer of vinyl chloride and triluorochloroethylene tenaciously adhered to the surface of said body.

5. The method of claim 4 wherein said layer is pigmented.

6. The method of claim 4 wherein said layer is pigmented, the volume ratio of pigment to said last-named resinous copolymer being equal to from 0.15 :1 to 0.4:1.

7. The method which comprises applying to the surface of a normally hard, tough, thermoplastic body composed of a uniform thermoplastic mixture of from 60 to 90% of a resinous copolymer of styrene and acrylonitle, in proportions of from to 90% of styrene and from 50 to 10% of acrylonitrile, and from 40 to 10% of a rubbery copolymer of butadiene and acryloninile, a relatively thin continuous layer of a lacquer comprising pigment and a resinous copolymer consisting essentially of from 30 to 95% Vinyl chloride and from 70 to 5% triuorochloroethylene dissolved in a volatile organic solvent for the last-named resinous copolymer, and evaporating said solvent to form a thin continuous layer of pigmented resinous copolymer of vinyl chloride and trifiuorochloroethylene adhered to the surface of said body.

8. The method which comprises applying to the surface of a normally hard, tough, thermoplastic body coniposed of a uniform thermoplastic mixture selected from the group consisting of mixtures of from to 90% of a resinous copolymer of styrene and acrylonitrile, in proportions of from 50 to 90% of styrene and from 50 to 10% of acrylonitrile, and from 40 to 10% of a rubbery copolymer of butadiene and acrylonitrile, and mixtures of from 60 to 90% of a resinous copolymer of styrene and butadiene, in proportions of from to 95% of styrene and from 25 to 5% of butadiene, and from 40 to 10% of a rubbery copolymer of butadiene and styrene, a relatively thin continuous layer comprising pigment and a resinous copolymer consisting essentially of from 5 to 95% vinyl chloride and from 95 to 5% trifluorochloro ethylene dissolved in a volatile organic solvent for the last-named resinous copolymer, said solvent composed of a mixture of two organic liquids, one of which is substantially a non-solvent for the rubbery and resinous cornponents of said body, the other of which is a solvent for said rubber and resin components of said body, and evaporating said solvent to form a thin continuous layer of pigmented resinous copolymer of vinyl chloride and trifluorochloroethylene tenaciously adhered to the surface of said body.

9. The method of claim 4 wherein said solvent is composed of from to 96% of an organic liquid which is substantially a non-solvent for the components of said mixture and correspondingly from l5 to 4% of a saturated aliphatic ketone.

References Cited in the le of this patent UNITED STATES PATENTS 2,479,367 Joyce et al Aug. 16, 1949 2,550,139 Daly Apr. 24, 1951 2,705,691 Panagrossi et al. Apr. 5, 1955 

4. THE METHOD WHICH COMPRISES APPLYING TO THE SURFACE OF A NORMALLY HARD, TOUGH, THERMOPLASTIC BODY COMPOSED OF A UNIFORM THERMOPLASTIC MIXTURE SELECTED FROM THE GROUP CONSISTING OF MIXTURE OF FROM 60 TO 90% OF A RESINOUS COPYOLYMER OF STYRENE AND ACRYLONITRILE, IN PROPORTIONS OFF FROM 50 TO 90% OF STYRENE AND FROM 50 TO 1% OF ACRYLONITRILE, AND FROM 40 TO 10% OF A RUBBERY COPOLYMER OF BUTADIENE AND ACRYLONITEILE, AND MIXTURES OF FROM 60 TO 90% OF A RESINOUS COPOLYMER OF STYRENE AND BUTADIENE, IN PROPORTIONS OF FROM 75 TO 95% OF STYRENE AND FROM 25 TO 5% OF BUTADIENE, AND FROM 40 TO 10% OF A RUBBERY COPOLYMER OF BUTADIENE AND STYRENE, A RELATIVELY THIN CONTINUOUS LAYER COMPRISING A RESINOUS COPOLYMER CONSISTING ESSENTIALLY OF FROM 30 TO 95% VINYL CHLORIDE AND FROM 70 TO 5% TRIFLUOROCHLORETHYLENE DISSOLVED IN A VOLATILE ORGANIC SOLVENT FOR THE LAST-NAMED RESINOUS COPOLYMER, AND EVAPORATING SAID SOLVENT TO FROM A THIN CONTINUOUS LAYER OF A RESINOUS COPOLYMER OF VINYL CHLORIDE AND TRIFLUOROCHLORETHYLENE TENACIOUSLY ADHERED TO THE SURFACE OF SAID BODY. 